use askama::Template;
use axum::{
    Form, Router,
    extract::{Multipart, Path, State},
    response::{Html, Redirect},
    routing::{get, post},
};
use rusqlite::params;
use serde::Deserialize;

use crate::auth::CurrentUser;
use crate::models::Instance;
use crate::routes::AppState;

#[derive(Template)]
#[template(path = "instances/list.html")]
struct InstanceListTemplate {
    username: String,
    is_superuser: bool,
    password_change_required: bool,
    instances: Vec<InstanceInfo>,
}

#[derive(Template)]
#[template(path = "instances/create.html")]
struct CreateInstanceTemplate {
    username: String,
    is_superuser: bool,
    password_change_required: bool,
    versions: Vec<String>,
    max_memory_mb: u32,
    error: Option<String>,
}

#[derive(Template)]
#[template(path = "instances/edit.html")]
struct EditInstanceTemplate {
    username: String,
    is_superuser: bool,
    password_change_required: bool,
    instance: Instance,
    current_seed: Option<String>,
    max_memory_mb: u32,
}

struct InstanceInfo {
    id: i64,
    name: String,
    version: String,
    server_type: String,
    is_active: bool,
    has_modpack: bool,
}

#[derive(Debug, Deserialize)]
pub struct CreateInstanceForm {
    pub name: String,
    pub version: String,
    pub server_type: String,
    pub world_source: String,
    pub seed: Option<String>,
    pub level_type: Option<String>,
    pub memory_mb: i32,
    pub difficulty: i32,
    pub gamemode: i32,
    pub max_players: i32,
    pub pvp: Option<String>,
    pub motd: Option<String>,
}

#[derive(Debug, Deserialize)]
pub struct EditInstanceForm {
    pub difficulty: i32,
    pub gamemode: i32,
    pub max_players: i32,
    pub pvp: Option<String>,
    pub motd: Option<String>,
    pub memory_mb: i32,
}

pub fn router() -> Router<AppState> {
    Router::new()
        .route("/instances", get(list_instances))
        .route("/instances/new", get(create_form))
        .route("/instances/new", post(create_instance))
        .route("/instances/{id}/edit", get(edit_form))
        .route("/instances/{id}/edit", post(edit_instance))
        .route("/instances/{id}/delete", post(delete_instance))
        .route("/instances/{id}/activate", post(activate_instance))
        .route("/instances/deactivate", post(deactivate_instance))
        .route("/instances/{id}/world/export", get(export_world))
        .route("/instances/{id}/world/import", post(import_world))
        .route("/instances/{id}/world/regenerate", post(regenerate_world))
}

async fn list_instances(
    State(state): State<AppState>,
    CurrentUser(account): CurrentUser,
) -> Result<Html<String>, axum::response::Redirect> {
    let conn = state.db.conn();
    let mut stmt = conn
        .prepare("SELECT id, name, version, server_type, is_active, has_modpack FROM instances ORDER BY name")
        .map_err(|_| Redirect::to("/login"))?;

    let instances: Vec<InstanceInfo> = stmt
        .query_map([], |row| {
            Ok(InstanceInfo {
                id: row.get(0)?,
                name: row.get(1)?,
                version: row.get(2)?,
                server_type: row.get(3)?,
                is_active: row.get::<_, i32>(4)? != 0,
                has_modpack: row.get::<_, i32>(5)? != 0,
            })
        })
        .map_err(|_| Redirect::to("/login"))?
        .filter_map(|r| r.ok())
        .collect();

    drop(stmt);
    drop(conn);

    let template = InstanceListTemplate {
        username: account.username.clone(),
        is_superuser: account.is_superuser,
        password_change_required: account.password_change_required,
        instances,
    };

    Ok(Html(template.render().unwrap_or_default()))
}

async fn create_form(
    State(state): State<AppState>,
    CurrentUser(account): CurrentUser,
) -> Result<Html<String>, axum::response::Redirect> {
    let versions = fetch_minecraft_versions().await.unwrap_or_else(|_| {
        vec![
            "1.21".into(),
            "1.20.6".into(),
            "1.20.1".into(),
            "1.19.4".into(),
            "1.12.2".into(),
        ]
    });

    let template = CreateInstanceTemplate {
        username: account.username.clone(),
        is_superuser: account.is_superuser,
        password_change_required: account.password_change_required,
        versions,
        max_memory_mb: state.config.max_memory_mb,
        error: None,
    };

    Ok(Html(template.render().unwrap_or_default()))
}

async fn create_instance(
    State(state): State<AppState>,
    CurrentUser(_user): CurrentUser,
    Form(form): Form<CreateInstanceForm>,
) -> Result<Redirect, axum::response::Redirect> {
    if form.memory_mb > state.config.max_memory_mb as i32 || form.memory_mb < 512 {
        return Ok(Redirect::to("/instances/new"));
    }

    let rcon_password = generate_rcon_password();
    let pvp = form.pvp.as_deref() == Some("on");
    let motd = form.motd.unwrap_or_else(|| "A Minecraft Server".into());
    let level_type = form.level_type.unwrap_or_else(|| "DEFAULT".into());
    let seed = form.seed.filter(|s| !s.is_empty());

    let conn = state.db.conn();
    conn.execute(
        "INSERT INTO instances (name, version, server_type, world_source, world_seed, level_type,
         memory_mb, difficulty, gamemode, max_players, pvp, motd, rcon_password, has_modpack)
         VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8, ?9, ?10, ?11, ?12, ?13, 0)",
        params![
            form.name,
            form.version,
            form.server_type,
            form.world_source,
            seed,
            level_type,
            form.memory_mb,
            form.difficulty,
            form.gamemode,
            form.max_players,
            pvp,
            motd,
            rcon_password,
        ],
    )
    .ok();
    drop(conn);

    let instance_dir = state
        .config
        .server_directory
        .join("instances")
        .join(&form.name)
        .join("data");
    let _ = std::fs::create_dir_all(&instance_dir);

    Ok(Redirect::to("/instances"))
}

#[axum::debug_handler]
async fn edit_form(
    State(state): State<AppState>,
    Path(id): Path<i64>,
    CurrentUser(account): CurrentUser,
) -> Result<Html<String>, axum::response::Redirect> {
    let instance = {
        let conn = state.db.conn();
        conn.query_row(
            "SELECT id, name, version, server_type, world_source, world_seed, level_type,
             has_modpack, memory_mb, difficulty, gamemode, max_players, pvp, motd,
             rcon_password, is_active, created_at, updated_at
             FROM instances WHERE id = ?1",
            params![id],
            |row| {
                Ok(Instance {
                    id: row.get(0)?,
                    name: row.get(1)?,
                    version: row.get(2)?,
                    server_type: row.get(3)?,
                    world_source: row.get(4)?,
                    world_seed: row.get(5)?,
                    level_type: row.get(6)?,
                    has_modpack: row.get::<_, i32>(7)? != 0,
                    memory_mb: row.get(8)?,
                    difficulty: row.get(9)?,
                    gamemode: row.get(10)?,
                    max_players: row.get(11)?,
                    pvp: row.get::<_, i32>(12)? != 0,
                    motd: row.get(13)?,
                    rcon_password: row.get(14)?,
                    is_active: row.get::<_, i32>(15)? != 0,
                    created_at: row.get(16)?,
                    updated_at: row.get(17)?,
                })
            },
        )
        .map_err(|_| Redirect::to("/instances"))?
    };

    let db_seed = instance.world_seed.clone().filter(|s| !s.is_empty());
    let current_seed =
        crate::properties::read_instance_seed(&state.config.server_directory, &instance.name)
            .or(db_seed);

    // If no seed known yet, try RCON /seed if the server is running
    let current_seed = if current_seed.is_none() && instance.is_active {
        let rcon = crate::rcon::RconClient::new(instance.rcon_password.clone());
        match rcon.send_command_async("seed".into()).await {
            Ok(resp) => {
                let s = resp.trim();
                // Format: "Seed: [1234567890]"
                s.strip_prefix("Seed: [")
                    .and_then(|r| r.strip_suffix(']'))
                    .or_else(|| s.strip_prefix("Seed: "))
                    .map(|v| v.trim().to_string())
            }
            Err(e) => {
                tracing::debug!("RCON /seed failed: {e}");
                None
            }
        }
    } else {
        current_seed
    };

    let template = EditInstanceTemplate {
        username: account.username.clone(),
        is_superuser: account.is_superuser,
        password_change_required: account.password_change_required,
        instance,
        current_seed,
        max_memory_mb: state.config.max_memory_mb,
    };

    Ok(Html(template.render().unwrap_or_default()))
}

async fn edit_instance(
    State(state): State<AppState>,
    Path(id): Path<i64>,
    CurrentUser(_user): CurrentUser,
    Form(form): Form<EditInstanceForm>,
) -> Result<Redirect, axum::response::Redirect> {
    if form.memory_mb > state.config.max_memory_mb as i32 || form.memory_mb < 512 {
        return Ok(Redirect::to(&format!("/instances/{id}/edit")));
    }

    let pvp = form.pvp.as_deref() == Some("on");

    let is_active = {
        let conn = state.db.conn();
        conn.execute(
            "UPDATE instances SET difficulty = ?1, gamemode = ?2, max_players = ?3,
             pvp = ?4, motd = ?5, memory_mb = ?6, updated_at = datetime('now')
             WHERE id = ?7",
            params![
                form.difficulty,
                form.gamemode,
                form.max_players,
                pvp,
                form.motd,
                form.memory_mb,
                id,
            ],
        )
        .map_err(|_| Redirect::to("/instances"))?;

        conn.query_row(
            "SELECT is_active FROM instances WHERE id = ?1",
            params![id],
            |row| row.get::<_, i32>(0).map(|v| v != 0),
        )
        .unwrap_or(false)
    };

    if is_active {
        let _ = state.docker.stop_container().await;
    }

    Ok(Redirect::to("/instances"))
}

async fn delete_instance(
    State(state): State<AppState>,
    Path(id): Path<i64>,
    CurrentUser(_user): CurrentUser,
) -> Result<Redirect, axum::response::Redirect> {
    let conn = state.db.conn();
    let is_active: bool = conn
        .query_row(
            "SELECT is_active FROM instances WHERE id = ?1",
            params![id],
            |row| row.get::<_, i32>(0).map(|v| v != 0),
        )
        .unwrap_or(false);

    if is_active {
        drop(conn);
        return Ok(Redirect::to("/instances"));
    }

    let name: Option<String> = conn
        .query_row(
            "SELECT name FROM instances WHERE id = ?1",
            params![id],
            |row| row.get(0),
        )
        .ok();

    conn.execute("DELETE FROM instances WHERE id = ?1", params![id])
        .ok();
    drop(conn);

    if let Some(name) = name {
        let instance_dir = state.config.server_directory.join("instances").join(&name);
        let _ = std::fs::remove_dir_all(&instance_dir);
    }

    Ok(Redirect::to("/instances"))
}

#[axum::debug_handler]
async fn activate_instance(
    State(state): State<AppState>,
    Path(id): Path<i64>,
    CurrentUser(_user): CurrentUser,
) -> Result<Redirect, axum::response::Redirect> {
    // Stop any running container first (this is usually fast)
    let _ = state.docker.stop_container().await;

    // Update DB: deactivate all, activate the new one
    let instance = {
        let conn = state.db.conn();
        conn.execute("UPDATE instances SET is_active = 0 WHERE is_active = 1", [])
            .ok();
        conn.execute(
            "UPDATE instances SET is_active = 1, updated_at = datetime('now') WHERE id = ?1",
            params![id],
        )
        .ok();

        conn.query_row(
            "SELECT id, name, version, server_type, world_source, world_seed, level_type,
             has_modpack, memory_mb, difficulty, gamemode, max_players, pvp, motd,
             rcon_password, is_active, created_at, updated_at
             FROM instances WHERE id = ?1",
            params![id],
            |row| {
                Ok(Instance {
                    id: row.get(0)?,
                    name: row.get(1)?,
                    version: row.get(2)?,
                    server_type: row.get(3)?,
                    world_source: row.get(4)?,
                    world_seed: row.get(5)?,
                    level_type: row.get(6)?,
                    has_modpack: row.get::<_, i32>(7)? != 0,
                    memory_mb: row.get(8)?,
                    difficulty: row.get(9)?,
                    gamemode: row.get(10)?,
                    max_players: row.get(11)?,
                    pvp: row.get::<_, i32>(12)? != 0,
                    motd: row.get(13)?,
                    rcon_password: row.get(14)?,
                    is_active: row.get::<_, i32>(15)? != 0,
                    created_at: row.get(16)?,
                    updated_at: row.get(17)?,
                })
            },
        )
        .map_err(|_| Redirect::to("/instances"))?
    };

    // Pull image + start container in background so the UI stays responsive
    let docker = state.docker.clone();
    let db = state.db.clone();
    let rcon_pw = instance.rcon_password.clone();
    tokio::spawn(async move {
        {
            let conn = db.conn();
            conn.execute(
                "UPDATE instances SET container_state = 'pulling' WHERE is_active = 1",
                [],
            )
            .ok();
        }
        match docker.start_container(&instance).await {
            Ok(()) => {
                {
                    let conn = db.conn();
                    conn.execute(
                        "UPDATE instances SET container_state = 'booting' WHERE is_active = 1",
                        [],
                    )
                    .ok();
                }
                // Wait for Minecraft to be ready via RCON
                let rcon = crate::rcon::RconClient::new(rcon_pw);
                for _ in 0..30 {
                    tokio::time::sleep(std::time::Duration::from_secs(2)).await;
                    if rcon.send_command_async("list".into()).await.is_ok() {
                        let conn = db.conn();
                        conn.execute(
                            "UPDATE instances SET container_state = 'running' WHERE is_active = 1",
                            [],
                        )
                        .ok();
                        tracing::info!("Server is ready (RCON responded)");
                        return;
                    }
                }
                tracing::error!("Server did not become ready within 60 seconds");
                let conn = db.conn();
                conn.execute(
                    "UPDATE instances SET container_state = 'error' WHERE is_active = 1",
                    [],
                )
                .ok();
            }
            Err(e) => {
                tracing::error!("Failed to start container: {e}");
                let conn = db.conn();
                conn.execute(
                    "UPDATE instances SET container_state = 'error' WHERE is_active = 1",
                    [],
                )
                .ok();
            }
        }
    });

    Ok(Redirect::to("/instances"))
}

async fn deactivate_instance(
    State(state): State<AppState>,
    CurrentUser(_user): CurrentUser,
) -> Result<Redirect, axum::response::Redirect> {
    let _ = state.docker.stop_container().await;

    let conn = state.db.conn();
    conn.execute(
        "UPDATE instances SET is_active = 0, container_state = 'stopped' WHERE is_active = 1",
        [],
    )
    .ok();
    drop(conn);

    Ok(Redirect::to("/instances"))
}

fn generate_rcon_password() -> String {
    use rand::Rng;
    let mut rng = rand::thread_rng();
    let chars: Vec<char> = "abcdefghijklmnopqrstuvwxyz0123456789".chars().collect();
    (0..16)
        .map(|_| chars[rng.gen_range(0..chars.len())])
        .collect()
}

async fn fetch_minecraft_versions() -> Result<Vec<String>, String> {
    let client = reqwest::Client::new();
    let manifest: serde_json::Value = client
        .get("https://piston-meta.mojang.com/mc/game/version_manifest_v2.json")
        .send()
        .await
        .map_err(|e| e.to_string())?
        .json()
        .await
        .map_err(|e| e.to_string())?;

    let versions: Vec<String> = manifest["versions"]
        .as_array()
        .ok_or("Invalid version manifest")?
        .iter()
        .filter_map(|v| {
            let t = v["type"].as_str()?;
            if t == "release" {
                v["id"].as_str().map(String::from)
            } else {
                None
            }
        })
        .collect();

    Ok(versions)
}

// ── World management ──────────────────────────────────────────────

#[derive(Debug, Deserialize)]
pub struct RegenerateWorldForm {
    pub seed: Option<String>,
}

async fn export_world(
    State(state): State<AppState>,
    Path(id): Path<i64>,
    CurrentUser(_user): CurrentUser,
) -> Result<axum::response::Response, axum::response::Redirect> {
    let conn = state.db.conn();
    let instance_name: String = conn
        .query_row(
            "SELECT name FROM instances WHERE id = ?1",
            params![id],
            |row| row.get(0),
        )
        .map_err(|_| Redirect::to("/instances"))?;
    drop(conn);

    let world_dir = state
        .config
        .server_directory
        .join("instances")
        .join(&instance_name)
        .join("data")
        .join("world");

    let mut zip_buf = Vec::new();
    {
        let mut zip = zip::ZipWriter::new(std::io::Cursor::new(&mut zip_buf));
        let options: zip::write::FileOptions<'_, ()> =
            zip::write::FileOptions::default().compression_method(zip::CompressionMethod::Deflated);
        add_dir_to_zip(&mut zip, &world_dir, "", options)?;
        zip.finish().ok();
    }

    let filename = format!("{instance_name}_world.zip");
    Ok(axum::response::Response::builder()
        .header(axum::http::header::CONTENT_TYPE, "application/zip")
        .header(
            axum::http::header::CONTENT_DISPOSITION,
            format!("attachment; filename=\"{filename}\""),
        )
        .body(axum::body::Body::from(zip_buf))
        .unwrap())
}

fn add_dir_to_zip(
    zip: &mut zip::ZipWriter<std::io::Cursor<&mut Vec<u8>>>,
    dir: &std::path::Path,
    prefix: &str,
    options: zip::write::FileOptions<'_, ()>,
) -> Result<(), axum::response::Redirect> {
    if let Ok(entries) = std::fs::read_dir(dir) {
        for entry in entries.flatten() {
            let path = entry.path();
            let name = path.file_name().unwrap().to_string_lossy();
            let zip_path = if prefix.is_empty() {
                name.to_string()
            } else {
                format!("{prefix}/{name}")
            };
            if path.is_dir() {
                zip.add_directory(&zip_path, options).ok();
                add_dir_to_zip(zip, &path, &zip_path, options)?;
            } else if let Ok(contents) = std::fs::read(&path) {
                zip.start_file(&zip_path, options).ok();
                std::io::Write::write_all(zip, &contents).ok();
            }
        }
    }
    Ok(())
}

#[axum::debug_handler]
async fn import_world(
    State(state): State<AppState>,
    Path(id): Path<i64>,
    CurrentUser(_user): CurrentUser,
    mut multipart: Multipart,
) -> Result<Redirect, axum::response::Redirect> {
    let (instance_name, is_active) = {
        let conn = state.db.conn();
        let row = conn.query_row(
            "SELECT name, is_active FROM instances WHERE id = ?1",
            params![id],
            |row| Ok((row.get::<_, String>(0)?, row.get::<_, i32>(1)? != 0)),
        );
        match row {
            Ok(v) => v,
            Err(_) => return Ok(Redirect::to("/instances")),
        }
    };

    if is_active {
        return Ok(Redirect::to(&format!("/instances/{id}/edit")));
    }

    let data_dir = state
        .config
        .server_directory
        .join("instances")
        .join(&instance_name)
        .join("data");

    // Extract uploaded ZIP
    while let Ok(Some(field)) = multipart.next_field().await {
        let bytes = field
            .bytes()
            .await
            .map_err(|_| Redirect::to(&format!("/instances/{id}/edit")))?;
        let cursor = std::io::Cursor::new(bytes);
        let mut archive = zip::ZipArchive::new(cursor)
            .map_err(|_| Redirect::to(&format!("/instances/{id}/edit")))?;

        // Remove existing world
        let world_dir = data_dir.join("world");
        let _ = std::fs::remove_dir_all(&world_dir);
        let _ = std::fs::create_dir_all(&world_dir);

        for i in 0..archive.len() {
            let mut file = archive
                .by_index(i)
                .map_err(|_| Redirect::to(&format!("/instances/{id}/edit")))?;
            let out_path = match file.enclosed_name() {
                Some(p) => world_dir.join(p),
                None => continue,
            };
            if file.is_dir() {
                let _ = std::fs::create_dir_all(&out_path);
            } else {
                if let Some(parent) = out_path.parent() {
                    let _ = std::fs::create_dir_all(parent);
                }
                let mut out = std::fs::File::create(&out_path)
                    .map_err(|_| Redirect::to(&format!("/instances/{id}/edit")))?;
                std::io::copy(&mut file, &mut out).ok();
            }
        }
        break; // only process first file
    }

    Ok(Redirect::to(&format!("/instances/{id}/edit")))
}

async fn regenerate_world(
    State(state): State<AppState>,
    Path(id): Path<i64>,
    CurrentUser(_user): CurrentUser,
    Form(form): Form<RegenerateWorldForm>,
) -> Result<Redirect, axum::response::Redirect> {
    let conn = state.db.conn();
    let (instance_name, is_active): (String, bool) = conn
        .query_row(
            "SELECT name, is_active FROM instances WHERE id = ?1",
            params![id],
            |row| Ok((row.get(0)?, row.get::<_, i32>(1)? != 0)),
        )
        .map_err(|_| Redirect::to("/instances"))?;
    drop(conn);

    if is_active {
        return Ok(Redirect::to(&format!("/instances/{id}/edit")));
    }

    let props_path = state
        .config
        .server_directory
        .join("instances")
        .join(&instance_name)
        .join("data")
        .join("server.properties");

    // Update level-seed in server.properties
    let seed = form.seed.unwrap_or_default();
    let contents = std::fs::read_to_string(&props_path).unwrap_or_default();
    let mut new_lines = Vec::new();
    let mut found = false;
    for line in contents.lines() {
        if line.trim_start().starts_with("level-seed") {
            new_lines.push(format!("level-seed={seed}"));
            found = true;
        } else {
            new_lines.push(line.to_string());
        }
    }
    if !found {
        new_lines.push(format!("level-seed={seed}"));
    }
    let _ = std::fs::write(&props_path, new_lines.join("\n"));

    // Update DB record
    let db_seed: Option<&str> = if seed.is_empty() { None } else { Some(&seed) };
    let conn = state.db.conn();
    conn.execute(
        "UPDATE instances SET world_seed = ?1, updated_at = datetime('now') WHERE id = ?2",
        params![db_seed, id],
    )
    .ok();
    drop(conn);

    // Delete existing world so it gets regenerated on next start
    let world_dir = state
        .config
        .server_directory
        .join("instances")
        .join(&instance_name)
        .join("data")
        .join("world");
    let _ = std::fs::remove_dir_all(&world_dir);

    Ok(Redirect::to(&format!("/instances/{id}/edit")))
}